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   1 /*
   2  * linux/kernel/irq/manage.c
   3  *
   4  * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
   5  * Copyright (C) 2005-2006 Thomas Gleixner
   6  *
   7  * This file contains driver APIs to the irq subsystem.
   8  */
   9
  10 #include <linux/irq.h>
  11 #include <linux/module.h>
  12 #include <linux/random.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/slab.h>
  15
  16 #include "internals.h"
  17
  18 #ifdef CONFIG_SMP
  19
  20 cpumask_t irq_default_affinity = CPU_MASK_ALL;
  21
  22 /**
  23  *      synchronize_irq - wait for pending IRQ handlers (on other CPUs)
  24  *      @irq: interrupt number to wait for
  25  *
  26  *      This function waits for any pending IRQ handlers for this interrupt
  27  *      to complete before returning. If you use this function while
  28  *      holding a resource the IRQ handler may need you will deadlock.
  29  *
  30  *      This function may be called - with care - from IRQ context.
  31  */
  32 void synchronize_irq(unsigned int irq)
  33 {
  34         struct irq_desc *desc = irq_to_desc(irq);
  35         unsigned int status;
  36
  37         if (!desc)
  38                 return;
  39
  40         do {
  41                 unsigned long flags;
  42
  43                 /*
  44                  * Wait until we're out of the critical section.  This might
  45                  * give the wrong answer due to the lack of memory barriers.
  46                  */
  47                 while (desc->status & IRQ_INPROGRESS)
  48                         cpu_relax();
  49
  50                 /* Ok, that indicated we're done: double-check carefully. */
  51                 spin_lock_irqsave(&desc->lock, flags);
  52                 status = desc->status;
  53                 spin_unlock_irqrestore(&desc->lock, flags);
  54
  55                 /* Oops, that failed? */
  56         } while (status & IRQ_INPROGRESS);
  57 }
  58 EXPORT_SYMBOL(synchronize_irq);
  59
  60 /**
  61  *      irq_can_set_affinity - Check if the affinity of a given irq can be set
  62  *      @irq:           Interrupt to check
  63  *
  64  */
  65 int irq_can_set_affinity(unsigned int irq)
  66 {
  67         struct irq_desc *desc = irq_to_desc(irq);
  68
  69         if (CHECK_IRQ_PER_CPU(desc->status) || !desc->chip ||
  70             !desc->chip->set_affinity)
  71                 return 0;
  72
  73         return 1;
  74 }
  75
  76 /**
  77  *      irq_set_affinity - Set the irq affinity of a given irq
  78  *      @irq:           Interrupt to set affinity
  79  *      @cpumask:       cpumask
  80  *
  81  */
  82 int irq_set_affinity(unsigned int irq, cpumask_t cpumask)
  83 {
  84         struct irq_desc *desc = irq_to_desc(irq);
  85         unsigned long flags;
  86
  87         if (!desc->chip->set_affinity)
  88                 return -EINVAL;
  89
  90         spin_lock_irqsave(&desc->lock, flags);
  91
  92 #ifdef CONFIG_GENERIC_PENDING_IRQ
  93         if (desc->status & IRQ_MOVE_PCNTXT || desc->status & IRQ_DISABLED) {
  94                 desc->affinity = cpumask;
  95                 desc->chip->set_affinity(irq, cpumask);
  96         } else {
  97                 desc->status |= IRQ_MOVE_PENDING;
  98                 desc->pending_mask = cpumask;
  99         }
 100 #else
 101         desc->affinity = cpumask;
 102         desc->chip->set_affinity(irq, cpumask);
 103 #endif
 104         desc->status |= IRQ_AFFINITY_SET;
 105         spin_unlock_irqrestore(&desc->lock, flags);
 106         return 0;
 107 }
 108
 109 #ifndef CONFIG_AUTO_IRQ_AFFINITY
 110 /*
 111  * Generic version of the affinity autoselector.
 112  */
 113 int do_irq_select_affinity(unsigned int irq, struct irq_desc *desc)
 114 {
 115         cpumask_t mask;
 116
 117         if (!irq_can_set_affinity(irq))
 118                 return 0;
 119
 120         cpus_and(mask, cpu_online_map, irq_default_affinity);
 121
 122         /*
 123          * Preserve an userspace affinity setup, but make sure that
 124          * one of the targets is online.
 125          */
 126         if (desc->status & (IRQ_AFFINITY_SET | IRQ_NO_BALANCING)) {
 127                 if (cpus_intersects(desc->affinity, cpu_online_map))
 128                         mask = desc->affinity;
 129                 else
 130                         desc->status &= ~IRQ_AFFINITY_SET;
 131         }
 132
 133         desc->affinity = mask;
 134         desc->chip->set_affinity(irq, mask);
 135
 136         return 0;
 137 }
 138 #else
 139 static inline int do_irq_select_affinity(unsigned int irq, struct irq_desc *d)
 140 {
 141         return irq_select_affinity(irq);
 142 }
 143 #endif
 144
 145 /*
 146  * Called when affinity is set via /proc/irq
 147  */
 148 int irq_select_affinity_usr(unsigned int irq)
 149 {
 150         struct irq_desc *desc = irq_to_desc(irq);
 151         unsigned long flags;
 152         int ret;
 153
 154         spin_lock_irqsave(&desc->lock, flags);
 155         ret = do_irq_select_affinity(irq, desc);
 156         spin_unlock_irqrestore(&desc->lock, flags);
 157
 158         return ret;
 159 }
 160
 161 #else
 162 static inline int do_irq_select_affinity(int irq, struct irq_desc *desc)
 163 {
 164         return 0;
 165 }
 166 #endif
 167
 168 /**
 169  *      disable_irq_nosync - disable an irq without waiting
 170  *      @irq: Interrupt to disable
 171  *
 172  *      Disable the selected interrupt line.  Disables and Enables are
 173  *      nested.
 174  *      Unlike disable_irq(), this function does not ensure existing
 175  *      instances of the IRQ handler have completed before returning.
 176  *
 177  *      This function may be called from IRQ context.
 178  */
 179 void disable_irq_nosync(unsigned int irq)
 180 {
 181         struct irq_desc *desc = irq_to_desc(irq);
 182         unsigned long flags;
 183
 184         if (!desc)
 185                 return;
 186
 187         spin_lock_irqsave(&desc->lock, flags);
 188         if (!desc->depth++) {
 189                 desc->status |= IRQ_DISABLED;
 190                 desc->chip->disable(irq);
 191         }
 192         spin_unlock_irqrestore(&desc->lock, flags);
 193 }
 194 EXPORT_SYMBOL(disable_irq_nosync);
 195
 196 /**
 197  *      disable_irq - disable an irq and wait for completion
 198  *      @irq: Interrupt to disable
 199  *
 200  *      Disable the selected interrupt line.  Enables and Disables are
 201  *      nested.
 202  *      This function waits for any pending IRQ handlers for this interrupt
 203  *      to complete before returning. If you use this function while
 204  *      holding a resource the IRQ handler may need you will deadlock.
 205  *
 206  *      This function may be called - with care - from IRQ context.
 207  */
 208 void disable_irq(unsigned int irq)
 209 {
 210         struct irq_desc *desc = irq_to_desc(irq);
 211
 212         if (!desc)
 213                 return;
 214
 215         disable_irq_nosync(irq);
 216         if (desc->action)
 217                 synchronize_irq(irq);
 218 }
 219 EXPORT_SYMBOL(disable_irq);
 220
 221 static void __enable_irq(struct irq_desc *desc, unsigned int irq)
 222 {
 223         switch (desc->depth) {
 224         case 0:
 225                 WARN(1, KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
 226                 break;
 227         case 1: {
 228                 unsigned int status = desc->status & ~IRQ_DISABLED;
 229
 230                 /* Prevent probing on this irq: */
 231                 desc->status = status | IRQ_NOPROBE;
 232                 check_irq_resend(desc, irq);
 233                 /* fall-through */
 234         }
 235         default:
 236                 desc->depth--;
 237         }
 238 }
 239
 240 /**
 241  *      enable_irq - enable handling of an irq
 242  *      @irq: Interrupt to enable
 243  *
 244  *      Undoes the effect of one call to disable_irq().  If this
 245  *      matches the last disable, processing of interrupts on this
 246  *      IRQ line is re-enabled.
 247  *
 248  *      This function may be called from IRQ context.
 249  */
 250 void enable_irq(unsigned int irq)
 251 {
 252         struct irq_desc *desc = irq_to_desc(irq);
 253         unsigned long flags;
 254
 255         if (!desc)
 256                 return;
 257
 258         spin_lock_irqsave(&desc->lock, flags);
 259         __enable_irq(desc, irq);
 260         spin_unlock_irqrestore(&desc->lock, flags);
 261 }
 262 EXPORT_SYMBOL(enable_irq);
 263
 264 /*
 265  * [ Not in kernel/irq/handle.c, so that GCC does not
 266  *   inline the __weak alias: ]
 267  */
 268 int __weak arch_init_chip_data(struct irq_desc *desc, int cpu)
 269 {
 270         return 0;
 271 }
 272
 273 static int set_irq_wake_real(unsigned int irq, unsigned int on)
 274 {
 275         struct irq_desc *desc = irq_to_desc(irq);
 276         int ret = -ENXIO;
 277
 278         if (desc->chip->set_wake)
 279                 ret = desc->chip->set_wake(irq, on);
 280
 281         return ret;
 282 }
 283
 284 /**
 285  *      set_irq_wake - control irq power management wakeup
 286  *      @irq:   interrupt to control
 287  *      @on:    enable/disable power management wakeup
 288  *
 289  *      Enable/disable power management wakeup mode, which is
 290  *      disabled by default.  Enables and disables must match,
 291  *      just as they match for non-wakeup mode support.
 292  *
 293  *      Wakeup mode lets this IRQ wake the system from sleep
 294  *      states like "suspend to RAM".
 295  */
 296 int set_irq_wake(unsigned int irq, unsigned int on)
 297 {
 298         struct irq_desc *desc = irq_to_desc(irq);
 299         unsigned long flags;
 300         int ret = 0;
 301
 302         /* wakeup-capable irqs can be shared between drivers that
 303          * don't need to have the same sleep mode behaviors.
 304          */
 305         spin_lock_irqsave(&desc->lock, flags);
 306         if (on) {
 307                 if (desc->wake_depth++ == 0) {
 308                         ret = set_irq_wake_real(irq, on);
 309                         if (ret)
 310                                 desc->wake_depth = 0;
 311                         else
 312                                 desc->status |= IRQ_WAKEUP;
 313                 }
 314         } else {
 315                 if (desc->wake_depth == 0) {
 316                         WARN(1, "Unbalanced IRQ %d wake disable\n", irq);
 317                 } else if (--desc->wake_depth == 0) {
 318                         ret = set_irq_wake_real(irq, on);
 319                         if (ret)
 320                                 desc->wake_depth = 1;
 321                         else
 322                                 desc->status &= ~IRQ_WAKEUP;
 323                 }
 324         }
 325
 326         spin_unlock_irqrestore(&desc->lock, flags);
 327         return ret;
 328 }
 329 EXPORT_SYMBOL(set_irq_wake);
 330
 331 /*
 332  * Internal function that tells the architecture code whether a
 333  * particular irq has been exclusively allocated or is available
 334  * for driver use.
 335  */
 336 int can_request_irq(unsigned int irq, unsigned long irqflags)
 337 {
 338         struct irq_desc *desc = irq_to_desc(irq);
 339         struct irqaction *action;
 340
 341         if (!desc)
 342                 return 0;
 343
 344         if (desc->status & IRQ_NOREQUEST)
 345                 return 0;
 346
 347         action = desc->action;
 348         if (action)
 349                 if (irqflags & action->flags & IRQF_SHARED)
 350                         action = NULL;
 351
 352         return !action;
 353 }
 354
 355 void compat_irq_chip_set_default_handler(struct irq_desc *desc)
 356 {
 357         /*
 358          * If the architecture still has not overriden
 359          * the flow handler then zap the default. This
 360          * should catch incorrect flow-type setting.
 361          */
 362         if (desc->handle_irq == &handle_bad_irq)
 363                 desc->handle_irq = NULL;
 364 }
 365
 366 int __irq_set_trigger(struct irq_desc *desc, unsigned int irq,
 367                 unsigned long flags)
 368 {
 369         int ret;
 370         struct irq_chip *chip = desc->chip;
 371
 372         if (!chip || !chip->set_type) {
 373                 /*
 374                  * IRQF_TRIGGER_* but the PIC does not support multiple
 375                  * flow-types?
 376                  */
 377                 pr_debug("No set_type function for IRQ %d (%s)\n", irq,
 378                                 chip ? (chip->name ? : "unknown") : "unknown");
 379                 return 0;
 380         }
 381
 382         /* caller masked out all except trigger mode flags */
 383         ret = chip->set_type(irq, flags);
 384
 385         if (ret)
 386                 pr_err("setting trigger mode %d for irq %u failed (%pF)\n",
 387                                 (int)flags, irq, chip->set_type);
 388         else {
 389                 if (flags & (IRQ_TYPE_LEVEL_LOW | IRQ_TYPE_LEVEL_HIGH))
 390                         flags |= IRQ_LEVEL;
 391                 /* note that IRQF_TRIGGER_MASK == IRQ_TYPE_SENSE_MASK */
 392                 desc->status &= ~(IRQ_LEVEL | IRQ_TYPE_SENSE_MASK);
 393                 desc->status |= flags;
 394         }
 395
 396         return ret;
 397 }
 398
 399 /*
 400  * Internal function to register an irqaction - typically used to
 401  * allocate special interrupts that are part of the architecture.
 402  */
 403 static int
 404 __setup_irq(unsigned int irq, struct irq_desc * desc, struct irqaction *new)
 405 {
 406         struct irqaction *old, **p;
 407         const char *old_name = NULL;
 408         unsigned long flags;
 409         int shared = 0;
 410         int ret;
 411
 412         if (!desc)
 413                 return -EINVAL;
 414
 415         if (desc->chip == &no_irq_chip)
 416                 return -ENOSYS;
 417         /*
 418          * Some drivers like serial.c use request_irq() heavily,
 419          * so we have to be careful not to interfere with a
 420          * running system.
 421          */
 422         if (new->flags & IRQF_SAMPLE_RANDOM) {
 423                 /*
 424                  * This function might sleep, we want to call it first,
 425                  * outside of the atomic block.
 426                  * Yes, this might clear the entropy pool if the wrong
 427                  * driver is attempted to be loaded, without actually
 428                  * installing a new handler, but is this really a problem,
 429                  * only the sysadmin is able to do this.
 430                  */
 431                 rand_initialize_irq(irq);
 432         }
 433
 434         /*
 435          * The following block of code has to be executed atomically
 436          */
 437         spin_lock_irqsave(&desc->lock, flags);
 438         p = &desc->action;
 439         old = *p;
 440         if (old) {
 441                 /*
 442                  * Can't share interrupts unless both agree to and are
 443                  * the same type (level, edge, polarity). So both flag
 444                  * fields must have IRQF_SHARED set and the bits which
 445                  * set the trigger type must match.
 446                  */
 447                 if (!((old->flags & new->flags) & IRQF_SHARED) ||
 448                     ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
 449                         old_name = old->name;
 450                         goto mismatch;
 451                 }
 452
 453 #if defined(CONFIG_IRQ_PER_CPU)
 454                 /* All handlers must agree on per-cpuness */
 455                 if ((old->flags & IRQF_PERCPU) !=
 456                     (new->flags & IRQF_PERCPU))
 457                         goto mismatch;
 458 #endif
 459
 460                 /* add new interrupt at end of irq queue */
 461                 do {
 462                         p = &old->next;
 463                         old = *p;
 464                 } while (old);
 465                 shared = 1;
 466         }
 467
 468         if (!shared) {
 469                 irq_chip_set_defaults(desc->chip);
 470
 471                 /* Setup the type (level, edge polarity) if configured: */
 472                 if (new->flags & IRQF_TRIGGER_MASK) {
 473                         ret = __irq_set_trigger(desc, irq,
 474                                         new->flags & IRQF_TRIGGER_MASK);
 475
 476                         if (ret) {
 477                                 spin_unlock_irqrestore(&desc->lock, flags);
 478                                 return ret;
 479                         }
 480                 } else
 481                         compat_irq_chip_set_default_handler(desc);
 482 #if defined(CONFIG_IRQ_PER_CPU)
 483                 if (new->flags & IRQF_PERCPU)
 484                         desc->status |= IRQ_PER_CPU;
 485 #endif
 486
 487                 desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING |
 488                                   IRQ_INPROGRESS | IRQ_SPURIOUS_DISABLED);
 489
 490                 if (!(desc->status & IRQ_NOAUTOEN)) {
 491                         desc->depth = 0;
 492                         desc->status &= ~IRQ_DISABLED;
 493                         desc->chip->startup(irq);
 494                 } else
 495                         /* Undo nested disables: */
 496                         desc->depth = 1;
 497
 498                 /* Exclude IRQ from balancing if requested */
 499                 if (new->flags & IRQF_NOBALANCING)
 500                         desc->status |= IRQ_NO_BALANCING;
 501
 502                 /* Set default affinity mask once everything is setup */
 503                 do_irq_select_affinity(irq, desc);
 504
 505         } else if ((new->flags & IRQF_TRIGGER_MASK)
 506                         && (new->flags & IRQF_TRIGGER_MASK)
 507                                 != (desc->status & IRQ_TYPE_SENSE_MASK)) {
 508                 /* hope the handler works with the actual trigger mode... */
 509                 pr_warning("IRQ %d uses trigger mode %d; requested %d\n",
 510                                 irq, (int)(desc->status & IRQ_TYPE_SENSE_MASK),
 511                                 (int)(new->flags & IRQF_TRIGGER_MASK));
 512         }
 513
 514         *p = new;
 515
 516         /* Reset broken irq detection when installing new handler */
 517         desc->irq_count = 0;
 518         desc->irqs_unhandled = 0;
 519
 520         /*
 521          * Check whether we disabled the irq via the spurious handler
 522          * before. Reenable it and give it another chance.
 523          */
 524         if (shared && (desc->status & IRQ_SPURIOUS_DISABLED)) {
 525                 desc->status &= ~IRQ_SPURIOUS_DISABLED;
 526                 __enable_irq(desc, irq);
 527         }
 528
 529         spin_unlock_irqrestore(&desc->lock, flags);
 530
 531         new->irq = irq;
 532         register_irq_proc(irq, desc);
 533         new->dir = NULL;
 534         register_handler_proc(irq, new);
 535
 536         return 0;
 537
 538 mismatch:
 539 #ifdef CONFIG_DEBUG_SHIRQ
 540         if (!(new->flags & IRQF_PROBE_SHARED)) {
 541                 printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
 542                 if (old_name)
 543                         printk(KERN_ERR "current handler: %s\n", old_name);
 544                 dump_stack();
 545         }
 546 #endif
 547         spin_unlock_irqrestore(&desc->lock, flags);
 548         return -EBUSY;
 549 }
 550
 551 /**
 552  *      setup_irq - setup an interrupt
 553  *      @irq: Interrupt line to setup
 554  *      @act: irqaction for the interrupt
 555  *
 556  * Used to statically setup interrupts in the early boot process.
 557  */
 558 int setup_irq(unsigned int irq, struct irqaction *act)
 559 {
 560         struct irq_desc *desc = irq_to_desc(irq);
 561
 562         return __setup_irq(irq, desc, act);
 563 }
 564
 565 /**
 566  *      free_irq - free an interrupt
 567  *      @irq: Interrupt line to free
 568  *      @dev_id: Device identity to free
 569  *
 570  *      Remove an interrupt handler. The handler is removed and if the
 571  *      interrupt line is no longer in use by any driver it is disabled.
 572  *      On a shared IRQ the caller must ensure the interrupt is disabled
 573  *      on the card it drives before calling this function. The function
 574  *      does not return until any executing interrupts for this IRQ
 575  *      have completed.
 576  *
 577  *      This function must not be called from interrupt context.
 578  */
 579 void free_irq(unsigned int irq, void *dev_id)
 580 {
 581         struct irq_desc *desc = irq_to_desc(irq);
 582         struct irqaction **p;
 583         unsigned long flags;
 584
 585         WARN_ON(in_interrupt());
 586
 587         if (!desc)
 588                 return;
 589
 590         spin_lock_irqsave(&desc->lock, flags);
 591         p = &desc->action;
 592         for (;;) {
 593                 struct irqaction *action = *p;
 594
 595                 if (action) {
 596                         struct irqaction **pp = p;
 597
 598                         p = &action->next;
 599                         if (action->dev_id != dev_id)
 600                                 continue;
 601
 602                         /* Found it - now remove it from the list of entries */
 603                         *pp = action->next;
 604
 605                         /* Currently used only by UML, might disappear one day.*/
 606 #ifdef CONFIG_IRQ_RELEASE_METHOD
 607                         if (desc->chip->release)
 608                                 desc->chip->release(irq, dev_id);
 609 #endif
 610
 611                         if (!desc->action) {
 612                                 desc->status |= IRQ_DISABLED;
 613                                 if (desc->chip->shutdown)
 614                                         desc->chip->shutdown(irq);
 615                                 else
 616                                         desc->chip->disable(irq);
 617                         }
 618                         spin_unlock_irqrestore(&desc->lock, flags);
 619                         unregister_handler_proc(irq, action);
 620
 621                         /* Make sure it's not being used on another CPU */
 622                         synchronize_irq(irq);
 623 #ifdef CONFIG_DEBUG_SHIRQ
 624                         /*
 625                          * It's a shared IRQ -- the driver ought to be
 626                          * prepared for it to happen even now it's
 627                          * being freed, so let's make sure....  We do
 628                          * this after actually deregistering it, to
 629                          * make sure that a 'real' IRQ doesn't run in
 630                          * parallel with our fake
 631                          */
 632                         if (action->flags & IRQF_SHARED) {
 633                                 local_irq_save(flags);
 634                                 action->handler(irq, dev_id);
 635                                 local_irq_restore(flags);
 636                         }
 637 #endif
 638                         kfree(action);
 639                         return;
 640                 }
 641                 printk(KERN_ERR "Trying to free already-free IRQ %d\n", irq);
 642 #ifdef CONFIG_DEBUG_SHIRQ
 643                 dump_stack();
 644 #endif
 645                 spin_unlock_irqrestore(&desc->lock, flags);
 646                 return;
 647         }
 648 }
 649 EXPORT_SYMBOL(free_irq);
 650
 651 /**
 652  *      request_irq - allocate an interrupt line
 653  *      @irq: Interrupt line to allocate
 654  *      @handler: Function to be called when the IRQ occurs
 655  *      @irqflags: Interrupt type flags
 656  *      @devname: An ascii name for the claiming device
 657  *      @dev_id: A cookie passed back to the handler function
 658  *
 659  *      This call allocates interrupt resources and enables the
 660  *      interrupt line and IRQ handling. From the point this
 661  *      call is made your handler function may be invoked. Since
 662  *      your handler function must clear any interrupt the board
 663  *      raises, you must take care both to initialise your hardware
 664  *      and to set up the interrupt handler in the right order.
 665  *
 666  *      Dev_id must be globally unique. Normally the address of the
 667  *      device data structure is used as the cookie. Since the handler
 668  *      receives this value it makes sense to use it.
 669  *
 670  *      If your interrupt is shared you must pass a non NULL dev_id
 671  *      as this is required when freeing the interrupt.
 672  *
 673  *      Flags:
 674  *
 675  *      IRQF_SHARED             Interrupt is shared
 676  *      IRQF_DISABLED   Disable local interrupts while processing
 677  *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
 678  *      IRQF_TRIGGER_*          Specify active edge(s) or level
 679  *
 680  */
 681 int request_irq(unsigned int irq, irq_handler_t handler,
 682                 unsigned long irqflags, const char *devname, void *dev_id)
 683 {
 684         struct irqaction *action;
 685         struct irq_desc *desc;
 686         int retval;
 687
 688 #ifdef CONFIG_LOCKDEP
 689         /*
 690          * Lockdep wants atomic interrupt handlers:
 691          */
 692         irqflags |= IRQF_DISABLED;
 693 #endif
 694         /*
 695          * Sanity-check: shared interrupts must pass in a real dev-ID,
 696          * otherwise we'll have trouble later trying to figure out
 697          * which interrupt is which (messes up the interrupt freeing
 698          * logic etc).
 699          */
 700         if ((irqflags & IRQF_SHARED) && !dev_id)
 701                 return -EINVAL;
 702
 703         desc = irq_to_desc(irq);
 704         if (!desc)
 705                 return -EINVAL;
 706
 707         if (desc->status & IRQ_NOREQUEST)
 708                 return -EINVAL;
 709         if (!handler)
 710                 return -EINVAL;
 711
 712         action = kmalloc(sizeof(struct irqaction), GFP_ATOMIC);
 713         if (!action)
 714                 return -ENOMEM;
 715
 716         action->handler = handler;
 717         action->flags = irqflags;
 718         cpus_clear(action->mask);
 719         action->name = devname;
 720         action->next = NULL;
 721         action->dev_id = dev_id;
 722
 723         retval = __setup_irq(irq, desc, action);
 724         if (retval)
 725                 kfree(action);
 726
 727 #ifdef CONFIG_DEBUG_SHIRQ
 728         if (irqflags & IRQF_SHARED) {
 729                 /*
 730                  * It's a shared IRQ -- the driver ought to be prepared for it
 731                  * to happen immediately, so let's make sure....
 732                  * We disable the irq to make sure that a 'real' IRQ doesn't
 733                  * run in parallel with our fake.
 734                  */
 735                 unsigned long flags;
 736
 737                 disable_irq(irq);
 738                 local_irq_save(flags);
 739
 740                 handler(irq, dev_id);
 741
 742                 local_irq_restore(flags);
 743                 enable_irq(irq);
 744         }
 745 #endif
 746         return retval;
 747 }
 748 EXPORT_SYMBOL(request_irq);